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#!/usr/bin/python -O
#
# /usr/sbin/webapp-config
# Python script for managing the deployment of web-based
# applications
#
# Originally written for the Gentoo Linux distribution
#
# Copyright (c) 1999-2007 Authors
# Released under v2 of the GNU GPL
#
# Author(s) Stuart Herbert
# Renat Lumpau <rl03@gentoo.org>
# Gunnar Wrobel <wrobel@gentoo.org>
#
# ========================================================================
'''
webapp-config needs a permission handling that allows to combine original
file permission settings with values supplied by the user.
'''
# ========================================================================
# Dependencies
# ------------------------------------------------------------------------
import re, grp, pwd
# ========================================================================
# Permission Helper
# ------------------------------------------------------------------------
# Mask
ALL = 7
READ = 4
WRITE = 2
EXECUTE = 1
# Shifting
USER = 6
GROUP = 3
OTHER = 0
class PermissionMap:
''' Permission Helper class that is initialized with a permission
mask. Subsequently the class can be used to combine this mask
with file permissions to generate a merged target value. '''
# Describes valid permission masks
valid = re.compile('^([ugoa]{1,4})([+-=])([rwx]{0,3})$')
def __call__(self, permissions):
''' "permissions" represents the last 9 bits of the permission
map as a normal integer (a value between 0 and 512).
Test the simple case:
>>> a = PermissionMap('0777')
>>> a(0644)
511
>>> a(0000)
511
>>> a = PermissionMap('o+x')
>>> a(0000)
1
>>> a = PermissionMap('ugo+rwx')
>>> a(0000)
511
>>> a = PermissionMap('u=rwx,g=x,o=w')
>>> a(0644)
458
>>> a = PermissionMap('u-rw,g=x,o+x')
>>> a(0644)
13
>>> a = PermissionMap('u-rwx,g-rwx,o-x')
>>> a(0751)
0
>>> a = PermissionMap('u=rw,g=r,o=')
>>> a(0000)
416
'''
# Check if the permissions are absolute
if self.__absolute:
return self.__permissions
else:
for i in self.__permissions:
# Permission mask. More complex
entity = self.valid.match(i).group(1)
operator = self.valid.match(i).group(2)
perm = self.valid.match(i).group(3)
# Generate the permission bits
perm_bit = 0
for i in perm:
if i == 'r':
perm_bit |= READ
if i == 'w':
perm_bit |= WRITE
if i == 'x':
perm_bit |= EXECUTE
for i in entity:
if i == 'u':
shift = [ USER ]
if i == 'g':
shift = [ GROUP ]
if i == 'o':
shift = [ OTHER ]
if i == 'a':
shift = [ USER, GROUP, OTHER ]
for j in shift:
if operator == '=':
permissions &= ~(ALL << j)
if operator == '-':
permissions &= ~(perm_bit << j)
if operator == '+' or operator == '=':
permissions |= (perm_bit << j)
return permissions
def __init__(self, permissions):
'''Check that the given permission map evaluates to something
useful.
"permissions" must be a string. It can either specify
absolute permissions as an octal number or it uses the
syntax for the unix chmod command (only
[ugoa]{1,4}[+-=][rxw]{1,3} as a comma-seperated list).
Check a few values:
>>> a = PermissionMap('0777')
>>> a = PermissionMap('0788')
Traceback (most recent call last):
...
Exception: Invalid permission string "0788"
>>> a = PermissionMap('u+r, go-wx')
>>> a = PermissionMap('u=+r,go-wx')
Traceback (most recent call last):
...
Exception: Invalid permission string "u=+r,go-wx"
>>> a = PermissionMap('u=rw,g=r,o=')
'''
self.__permissions = 0
# Simple case: absolute octal permission
if re.compile('[0-7]{4}').match(permissions):
self.__absolute = True
self.__permissions = eval("0o"+permissions)
else:
# Split on commas first
splitted_permissions = [ x.strip()
for x in permissions.split(',') ]
# Now analyze each part for correct structure
for i in splitted_permissions:
if not self.valid.match(i):
raise Exception('Invalid permission string "'
+ permissions + '"')
self.__permissions = splitted_permissions
self.__absolute = False
def __str__(self):
if self.__absolute:
return 'Absolute: {}'.format(oct(self.__permissions))
else:
return 'Relative: {}'.format(self.__permissions)
def get_group(group):
'''
Specify a group id either as integer, as string that can
be transformed into an integer or a string that matches
a group name.
>>> get_group(0)
0
>>> get_group('0')
0
>>> get_group('root')
0
>>> get_group('does_not_exist')
Traceback (most recent call last):
...
KeyError: 'The given group "does_not_exist" does not exist!'
'''
gid = -1
ngroup = -1
# Can we transform the value to an integer?
if not isinstance(group, int):
try:
ngroup = int(group)
except ValueError:
ngroup = -1
else:
# The value is an integer
ngroup = group
# Value was specified as integer or was transformed
if ngroup != -1:
try:
# Try to match the integer to a group id
gid = grp.getgrgid(ngroup)[2]
except KeyError:
pass
if gid == -1:
# No success yet. Try to match to the group name
try:
gid = grp.getgrnam(str(group))[2]
except KeyError:
raise KeyError('The given group "' + str(group)
+ '" does not exist!')
return gid
def get_user(user):
'''
Specify a user id either as integer, as string that can
be transformed into an integer or a string that matches
a user name.
>>> get_user(0)
0
>>> get_user('0')
0
>>> get_user('root')
0
>>> get_user('does_not_exist')
Traceback (most recent call last):
...
KeyError: 'The given user "does_not_exist" does not exist!'
'''
uid = -1
nuser = -1
# Can we transform the value to an integer?
if not isinstance(user, int):
try:
nuser = int(user)
except ValueError:
nuser = -1
else:
# The value is an integer
nuser = user
# Value was specified as integer or was transformed
if nuser != -1:
try:
# Try to match the integer to a user id
uid = pwd.getpwuid(nuser)[2]
except KeyError:
pass
if uid == -1:
# No success yet. Try to match to the user name
try:
uid = pwd.getpwnam(str(user))[2]
except KeyError:
raise KeyError('The given user "' + str(user)
+ '" does not exist!')
return uid
if __name__ == '__main__':
import doctest, sys
doctest.testmod(sys.modules[__name__])
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